The goal of this project is to determine as fully as experimental techniques allow the mechanism(s) by which macromolecules and macromolecular complexes cross the cell membrane. The systems under study are the localization of alkaline phosphatase at the cell surface in E coli, and the non-lytic release of the filamentous phage fd. These processes are being studied in bacterial mutants blocked at various steps in the synthesis of lipids in order to assess the role of membrane lipid in these processes.